mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-23 04:34:11 +08:00
ffa52d02c5
New versions of the SCSI dumper use the /dev/vmcore interface instead of zcore mem. Remove the outdated interface. Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
49 lines
2.3 KiB
Plaintext
49 lines
2.3 KiB
Plaintext
The s390 SCSI dump tool (zfcpdump)
|
|
|
|
System z machines (z900 or higher) provide hardware support for creating system
|
|
dumps on SCSI disks. The dump process is initiated by booting a dump tool, which
|
|
has to create a dump of the current (probably crashed) Linux image. In order to
|
|
not overwrite memory of the crashed Linux with data of the dump tool, the
|
|
hardware saves some memory plus the register sets of the boot CPU before the
|
|
dump tool is loaded. There exists an SCLP hardware interface to obtain the saved
|
|
memory afterwards. Currently 32 MB are saved.
|
|
|
|
This zfcpdump implementation consists of a Linux dump kernel together with
|
|
a user space dump tool, which are loaded together into the saved memory region
|
|
below 32 MB. zfcpdump is installed on a SCSI disk using zipl (as contained in
|
|
the s390-tools package) to make the device bootable. The operator of a Linux
|
|
system can then trigger a SCSI dump by booting the SCSI disk, where zfcpdump
|
|
resides on.
|
|
|
|
The user space dump tool accesses the memory of the crashed system by means
|
|
of the /proc/vmcore interface. This interface exports the crashed system's
|
|
memory and registers in ELF core dump format. To access the memory which has
|
|
been saved by the hardware SCLP requests will be created at the time the data
|
|
is needed by /proc/vmcore. The tail part of the crashed systems memory which
|
|
has not been stashed by hardware can just be copied from real memory.
|
|
|
|
To build a dump enabled kernel the kernel config option CONFIG_CRASH_DUMP
|
|
has to be set.
|
|
|
|
To get a valid zfcpdump kernel configuration use "make zfcpdump_defconfig".
|
|
|
|
The s390 zipl tool looks for the zfcpdump kernel and optional initrd/initramfs
|
|
under the following locations:
|
|
|
|
* kernel: <zfcpdump directory>/zfcpdump.image
|
|
* ramdisk: <zfcpdump directory>/zfcpdump.rd
|
|
|
|
The zfcpdump directory is defined in the s390-tools package.
|
|
|
|
The user space application of zfcpdump can reside in an intitramfs or an
|
|
initrd. It can also be included in a built-in kernel initramfs. The application
|
|
reads from /proc/vmcore or zcore/mem and writes the system dump to a SCSI disk.
|
|
|
|
The s390-tools package version 1.24.0 and above builds an external zfcpdump
|
|
initramfs with a user space application that writes the dump to a SCSI
|
|
partition.
|
|
|
|
For more information on how to use zfcpdump refer to the s390 'Using the Dump
|
|
Tools book', which is available from
|
|
http://www.ibm.com/developerworks/linux/linux390.
|